"They have no savoir-vivre," says a French woman about the two American heroines of 'Le Divorce' -- ironic, given that we've watched a fair amount of bad manners from French men. I think what the woman means is that American women who get involved with French guys have no idea what they're getting into -- even if they think they do -- and when the inevitable happens, they react like ... well, Americans.

At the start of Le Divorce, Isabel (Kate Hudson) arrives in Paris to visit her older sister Roxy (Naomi Watts), a poet who's married to French artist Charles-Henri (Melvil Poupaud) and expecting their second child. Isabel hardly has time to say hi to Charles-Henri before he's out the door, zooming off in the very taxi she arrived in. He's leaving Roxy for some (married) Russian woman. Roxy covers for him ("He's going to the country"), but can't keep it from Isabel for long.

Le Divorce, advertised as a comedy, is more of a semi-serious study of two sisters and two families. Kate Hudson, in probably the best role she's had in a while, provides the bubbles in this champagne; Naomi Watts, tense and thickening with child, grounds the movie in heartache. When Isabel takes up with a married politician (Thierry Lhermitte) who's also a member of Charles-Henri's clan, it's as if she's acting out revenge on her sister's behalf; she goes into the affair almost ironically, enacting the clichéd tryst with a married Frenchman, but she's not prepared for the feelings she develops towards him. She's also not prepared for Matthew Modine, who stomps into the picture on a wave of jealousy as the husband of the Russian woman Charles-Henri is seeing. The French women observe all this and sigh and shrug. Americans -- they know nothing of love. C'est la vie.

Director James Ivory frames the story (from a Diane Johnson novel) as a mixture of fluff and inquiry. We probably spend too much time on a subplot involving a La Tour painting, though it allows for welcome, relaxed comic relief from Sam Waterston and Stockard Channing as the sisters' parents, as well as the underused Bebe Neuwirth as a museum buyer with her eye on the art (her auction competitor is Stephen Fry -- nice to see him, too). Isabel takes a position assisting an American writer, who turns out to be Glenn Close looking elegant in long gray hair and, in one scene, blue-tinted little spectacles. Close's character takes one look at the pricey red Kelly purse Isabel is sporting and knows who gave it to her; she got one too, some years back.

The movie is least successful when it tips from semi-serious to too-serious. A suicide attempt is jarring and makes us look askance at the character afterward, and it's too easily recovered from and forgotten. A climactic bit in which the furious Modine stalks Isabel all the way up the Eiffel Tower feels like an outtake from a tepid Hitchcock homage.

But, this being a Paris-set movie, there's always something to look at, and Hudson and Watts, though perhaps cast a bit too on-the-nose (Kate gets to be frisky and cute, Naomi does her torment-held-barely-in-check thing as becomingly as usual), add some flavor and texture to the soap opera. They may lack savoir-vivre, but they bring some American feux d'artifice to the party.